The present invention relates to a flexible hose frequently used as a hose of a common electric vacuum cleaner. More particularly, the present invention relates to a flexible hose including reinforcing threads in which a coated conductive wire for electrical conduction is spirally wound and kept at the inner surface side of a synthetic resin pipe wall or in the pipe wall, and a plurality of reinforcing threads are disposed along a pipe axis direction between inner and outer layers of the pipe wall. The present invention also relates to a method of producing the same.
There is a conventional flexible hose, especially a cleaner hose, which is made of a synthetic resin and in which coated conductive wires for electrical conduction are disposed and kept in a pipe wall and reinforcing threads are provided around the outer surface of the pipe wall along the pipe axis direction as described in Japanese Utility Model Unexamined Publication No. Hei. 3-72856 filed by the present applicant.
As shown in FIGS. 7 and 8, in this conventional hose, two hard wire materials 13 and 13' as reinforcing wires are spirally wound in double pitches and buried in an inner wall 11 formed of double layers of two synthetic resin band materials 11a and 11b, and two coated conductive wires 12 and 12', each containing two conductive wires 12a and 12a' integrally coated with films 12c and 12c' which are connected through an intermediate portion 12b to form a cross section shaped like eye glasses, are spirally wound in double pitches around the respective hard wire materials 13 and 13'. As shown in FIG. 7, a plurality of reinforcing threads 16 are disposed on the outer surface thereof along the pipe axis direction with an appropriate interval in the circumferential direction. At the outer side thereof, a synthetic resin band material 14' having a width substantially equal to the double pitch width of the hard wire materials 13 and 13' are spirally wound, and the side edges of the band material 14' are overlapped with each other on the outer circumferential surface of one of the coated conductive wires to be integrally fused, and also fused to the inner wall 11, whereby an outer wall 14 is formed. The synthetic resin band material 14' forming the outer wall 14 has a width to be buried at the portions corresponding to two pitches of the two spirally wound coated conductive wires 12 and 12' at the same time.
In the conventional hose thus constructed, at the time of producing the hose, the synthetic resin band material 14' forming the outer wall 14 is spirally wound on the plurality of reinforcing threads 16 disposed along the pipe axis direction, and due to the winding pressure of the band material or by pressing the band material through pressing rolls or the like from the outer circumferential direction, the reinforcing threads 16 are pressed to the two bottom portions 15 at the same time so that the threads are disposed along the bottom portions 15 formed between the coated conductive wires 12 and 12' and pinched between the outer wall 14 and the inner wall 11. However, the respective reinforcing threads 16 pressed to the two bottom portions 15 are pulled in the right and left bottom portions so that is difficult to press the threads to be located till a corner portion of the bottom. Thus, the reinforcing threads 16 may rise at the corner portion of the bottom or partially rise due to inequable sinking in the right and left bottoms. As a result, the reinforcing threads 16 are pulled by a bending or pulling action during the usage of the hose, so that local cracks may be generated in the outer layer, or the inner and outer layers may be peeled away. That is, the conventional hose has a problem that the durability as the flexible hose is inferior.